Method and system for controlling an air mass flow in an aircraft

ABSTRACT

An air mass or volume flow in an aircraft is controlled in a closed loop control system. A controllable air distribution network is formed by pipes, ducts, valves, fans, a fresh air supply and climate packs. The generation of a closed loop control signal is based on a continuous recalculation or updating of rated performance characteristic data with regard to current pressure, temperature and altitude data. The updated data are compared with actually measured current data to produce the control signal. The rated performance characteristic data are stored in a memory connected to a connected ( 32 ) which also receives the current data. The sensing ascertains one or more temperature, pressure, altitude and flow volume data to provide current actually measured data which are then compared with the updated data for generating the closed loop control signal for at least certain of the valves, fans, and fresh air supply.

[0001] This application is based on and claims the priority under 35U.S.C. §119 of German Patent Application 100 00 669.8, filed on Jan. 11,2000, the entire disclosure of which is incorporated herein byreference.

FIELD OF THE INVENTION

[0002] An air mass or air volume flow, particularly in a distributionnetwork in a passenger aircraft cabin is controlled by controlling theflow through the distribution network in response to a plurality ofparameters such as the flight altitude, which parameters have aninfluence on the flow volume.

BACKGROUND INFORMATION

[0003] In aircraft and particularly in passenger aircraft it isimportant for the passengers' comfort that an air mass flow through thecabin is balanced. This means that the air volume supplied into thecabin must be balanced relative to the air volume taken out of the cabinat any altitude, at any temperature and at any cabin pressure. Pressuresand temperatures inside and outside of the aircraft are parameters thathave an influence on the air mass flow balance through the air flowdistribution network comprising pipes, ducts, valves, flaps, fans,blowers, at least one fresh air turbo-engine and one or more climatepacks in the aircraft fuselage.

[0004] The air mass flow in an aircraft frequently must be distributedto outlets or other air users in a variable manner. For controlling thisvariable distribution of the air volume, pressure loss characteristicsof the flow control elements are used as control values for adjustingthe flow control elements such as valves or other flow cross-sectionvarying devices in such a manner that the air distribution followsclosed loop control algorithms. These algorithms operate on the basis ofknown, determined, rated values for example of the pressure ortemperature of the air mass flow or air volume flow through the airdistribution network. The closed loop control rules for the variable airdistribution are determined as variable control values or in accordancewith the so-called two-point closed loop air control. Reference is madein this connection to air flow control systems in several Airbus Modelssuch as A300, A310, A319, A320, A321, A330, A340 and A300Fr-600R. Theseknown airflow control systems are referred to as closed loop trim airpressure control in trim air common air supply pipe.

[0005] More complex problems must be solved where it becomes necessaryto control an air mass or volume flow inside an involved air mass flowdistribution network simply referred to herein as network ordistribution network. Such networks include a plurality of pipes andducts connected to many air consumers and outlets that may requiredifferent air volumes to be controlled by different air distributionrules. Similar considerations apply where the entire air input volumeinto such an air distribution network is to be uniformly increased ordiminished. Efforts have been made in this connection to individuallycontrol the air mass or air volume in each individual pipe or duct ofthe network. The entire air volume supply has also been controlled byvarying the total air supply through variably controlling air supplyunits such as turbo-engines which supply fresh air into the distributionnetwork.

[0006] Conventional air flow or volume controls make use of flow data ofa common supply line of the network to provide control signals forcontrolling the air flow and supply. However, these conventionalcontrols are subject to air mass flow deviations that conventionallyhave not been corrected. Such deviations depend for example on thevariable flight altitude during ascent and descent flight and on theconstant flight altitude during cruising flight. The invention aims atproviding such an altitude correction of the air mass flow in the airdistribution network.

[0007] A so-called G+T fan control of turbo-engines that is responsiveto pressure, is known for maintaining a constant air volume supply isused in the Airbus Model A310. It is further known from European PatentPublication EP 0,926,979 A1 to control in closed loop fashion flowadjustment devices in response to the static pressure in the main airsupply line or duct to provide a variable air volume supply. However,such a control does not take into account that in an aircraft theoverall cabin pressure is variable. This variable overall pressuresubstantially influences the pressure loss characteristic of airdistribution network components or elements such as valves, pipes,ducts, turbo-engines, air conditioners, fans or blowers, etc.

[0008] German Patent Publication DE 43 16 886 A1 (Bloch et al.)describes an aircraft cabin pressure closed loop control device for anaircraft wherein a closed loop controller (3, 7) compares an actualvalue with a rated value of the cabin pressure. The resulting signal isused to control an air outlet valve (11). The air outlet valve (11) isdriven by a drive (10), the drive speed of which is controlled in closedloop fashion. The adjusted valve position itself is not sensed, merelythe cabin pressure is sensed. The actual cabin pressure depends on theair supply through the valve (11) and on the fresh air supply (13) intothe cabin. Thus, the valve adjustment speed is controlled exclusively inresponse to the difference between the rated cabin pressure value andthe actual pressure value without regard to the variable performancecharacteristic of the valve itself.

[0009] U.S. Pat. No. 5,273,486 (Emmons et al.) describes an aircraftcabin pressure control system which is adaptable to the requirements ofascent and decent flight with the help of ascent and descent scheduleswhich accommodate variable requirements of specific airlines, theairlines' route structures, and regional air traffic control standards.The Emmons system includes an adaptive control logic that identifies aplurality of points generated by the schedules that define ascent anddescent curves corresponding to anticipated cabin pressure change ratesduring ascent and descent. During aircraft flight, the logic samples andstores actual cabin pressure change rates at each of the plurality ofpoints. After the flight, the actual cabin pressure change rates areaveraged and the average rate is compared to the anticipated cabinpressure change rate at each point. An offset is then calculatedrepresenting the difference between the average actual rate and ananticipated rate, and the ascent and/or descent schedules are adapted bythe offset to bring the anticipated cabin pressure change rates closerto the average actual rate. After several flights, the ascent anddescent schedules are customized by the adaptive control logic to aparticular airline's requirements. Emmons et al., by expressly storingpressure change rates as a function of ascent and descent flightaltitudes for use in the cabin pressure control have not recognized theneed for considering other parameters for the control of air flowvolumes in an aircraft.

OBJECTS OF THE INVENTION

[0010] In view of the foregoing it is the aim of the invention toachieve the following objects singly or in combination:

[0011] to correct the air mass or volume flow into and out of anaircraft cabin by making corrections with regard to the instantaneousaltitude at which the aircraft is flying;

[0012] to control, in closed loop fashion, the air flow controllingelements in an air flow distribution network, such as valves,turbo-engines, fans or blowers in response to a function that takes intoaccount changes in the performance characteristics of these air flowcontrolling elements, whereby these performance changes depend onpressure, temperature and altitude changes during flight; and

[0013] to further take into account in the generation of the closedfeedback control signal, any measuring errors, any pressure losscharacteristics of the air flow controlling elements and the pressure,temperature and air flow volume inside the air distribution pipes andducts of the network; and

[0014] to correct or update standardized or rated performancecharacteristics of the air flow controlling elements with reference tocurrent pressure, temperature and altitude data to provide updatedperformance characteristics for comparing with actual performancecharacteristics to thereby generate a control signal for controlling theair flow volume under current operating conditions.

SUMMARY OF THE INVENTION

[0015] According to the invention the above objects have been achievedby a system for controlling, in closed loop fashion, an air mass flowinside an aircraft fuselage, said system comprising a controllable airmass flow distribution network including air flow pipes, at least oneair outlet connected to one of said air flow pipes, at least onecontrollable air flow control element such as a valve, a blower, and/ora turbine engine connected to the air flow pipe or pipes for moving airthrough said distribution network to said at least one air outlet. Thissystem further includes a closed loop control unit having a memory forstoring rated, first data representing at least one rated standardizedperformance characteristic of said controllable air flow control elementin said air mass flow distribution network, a plurality of sensorspositioned for sensing actual second data representing any one of actualperformance characteristics and actual pressure, temperature andaltitude data. The closed loop control unit further comprises or is partof a central processing unit including a computer connected to thememory and to pressure, temperature and altitude sensors for calculatingupdated performance characteristic rated data from said rated first dataand from the actual second data. A comparator is part of the CPU andincludes a first input connected to an output of said computer forreceiving said updated rated performance characteristic data.

[0016] The comparator has a second input connected to the sensors forreceiving said actual second data. The comparator has an outputconnected to the controllable air mass flow distribution networkspecifically to the controllable air flow control element or elementsfor providing a closed loop control signal for controlling the air massflow. The comparator output and thus the closed loop control signal areconnected through respective control signal busses to said at least onecontrollable air flow control element.

[0017] According to the invention the following data are acquired singlyor in combination through respective sensors for processing in a dataacquisition section of the closed loop control unit:

[0018] (1) air pressure inside any of the pipes and ducts of thedistribution network,

[0019] (2) air pressure outside of the network including cabin pressureand atmospheric pressure outside the aircraft,

[0020] (3) the air temperature inside the network,

[0021] (4) the air temperature outside the network including the cabintemperature and the temperature outside of the aircraft body,

[0022] (5) the air volume or mass flowing through the network, and

[0023] (6) the flight altitude.

[0024] Thus, various types of sensors and/or measuring devices are usedin combination according to the invention such as temperature sensors,pressure sensors, air volume flow sensors and altitude sensors. Thesesensors are connected with their outputs to the data acquisition sectionof the closed loop control unit or to a performance characteristicsupdating circuit. The data acquisition section processes the respectivesensor information or data to provide respective actual flow volumesignals to one input of the comparator. These flow volume signalsrepresent actual performance characteristics of the above mentionednetwork elements under the actual current pressure, temperature andaltitude conditions. The computer section for correcting or updatingrated performance characteristics stored in the memory provides updatedperformance characteristic values or data for comparing with the actualperformance characteristic values or data to produce closed loop controlsignals that will correct the operation of the controllable air flowcontrol elements, such as the mentioned valves, fans and a fresh airsupply, for example provided by a turbo-engine, which will be controlledwith due regard to any pressure loss in these network elements. Therated performance characteristics are established under standardizedoperating conditions on the ground and stored in the memory such as aROM. The invention has recognized that the rated operating conditionsmust be corrected or updated with reference to current operatingconditions when the standardized operating conditions such as groundlever and room temperature are no longer present.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order that the invention may be clearly understood, it willnow be described in connection with example embodiments, with referenceto the accompanying single drawing FIGURE showing a block diagram of theair mass flow closed loop control system according to the inventionwherein the air distribution network and the closed loop control unitare drawn in full lines and wherein dashed lines show electricalconductor or data bus connections.

DETAILED DESCRIPTION OF PREFERRED EXAMPLE EMBODIMENTS AND OF THE BESTMODE OF THE INVENTION

[0026] The single FIGURE shows a closed loop control unit 1 which ispreferably part of a central processing unit (CPU). The control unit 1includes a memory 2 for storing rated or standardized performancecharacteristic values or data relating to at least certain elements orcomponents of an air mass flow distribution system including pipes 9,ducts 7, 7′, 61′, 71, valves 51, 53 fans or blowers 52, a climate packor air conditioner 61, a fresh air distribution system 6, and at leastone turbo-engine 8 for providing fresh air. The network will bedescribed in more detail below. The control unit 1 or CPU furthercomprises a control output 3 of a comparing circuit 31 and a computer32. The computer 32 has stored in its memory (not shown) an algorithmfor calculating updated performance characteristic values based on datarepresenting standardized, rated performance characteristic curves orfields of such curves stored in a memory 2 of the CPU and on datareceived from sensors 11 and 12 which as such are part of the aircraftequipment. The data stored in the memory 2 represent rated performancecharacteristics of the ducts, fans, valves, etc. One input of thecomputer 32 is electrically connected to the memory 2 for receiving therated data while another input of the computer 32 is electricallyconnected to the sensors 11 and 12 for receiving actual pressure,temperature and altitude data. The comparing circuit or comparator 31has one input connected to the output of the computer 32 to receiveupdated rated performance characteristic values for comparing withactual data or values received at a second input of the comparator 31from a data acquisition and processing circuit 4. The control output 3of the comparator 31 is connected through control data busses 10A, 10B,10C, 10D and 10E to network elements, the performance of which must becontrolled. These elements are the valves 51, 53 the fans or blowers 52and the at least one fresh air supplying turbo-engine 8. Thus, thecontrol output 3 provides closed loop control signals to the justmentioned network elements to be controlled as will be described in moredetail below.

[0027] The data acquisition and processing circuit 4 has a plurality ofinputs connected through electrical sensor conductors or busses 10′ to aplurality of sensors. For example, a sensor 5 is provided directlyinside a common or main air supply duct 7 for measuring any one of thefollowing data, the pressure and/or the temperature and/or the volumeflow inside the duct 7. The duct 7 is connected to a plurality ofindividual branch lines 9 and to air users or air outlets 9′. The commonor main duct 7 receives air from a distribution duct 7′ which isconnected to at least one air conditioner or climate pack 61 through aduct 61′ feeding conditioned air into the distribution duct 7′ in whichthe air is transported by the air flow driving fans or blowers 52. Theoutputs of the fans or blowers 52 are connected to the main duct 7. Onlytwo individual branch lines 9 branch off directly from the main duct 7and lead to outlets 9′. However, a multitude of such branch lines 9 andoutlets 9′ may be used in practice. The aircraft fuselage merely shownsymbolically by an arrow F receives air from the duct 7 through acontrollable valve 51, preferably provided with its own performancesensor 51′ connected through a sensor conductor 10′ to an input of thedata acquisition circuit 4.

[0028] The air flow drive fans 52 are equipped with sensors 52′ formeasuring pressure loss characteristics of the fans 52. Signals fromthese sensors 52′ are supplied to a respective input of the dataacquisition circuit 4 through respective sensor conductors

[0029] Individual sensors 9″ are preferably provided in or on theindividual distribution pipes 9 or a fresh air connecting line 9A formeasuring temperature, pressure, and/or the flow volume through theseindividual distribution pipes 9, 9A to the users or outlets 9′.

[0030] Fresh air is supplied into the distribution network by at leastone turbine engine 8 connected to the individual distribution lines 9 bya fresh air supply line 71 leading into the fresh air connecting line 9Awhich leads to all outlets 9′. A flow control valve 53 and a fresh airdistribution system 6 are connected in the fresh air supply line 71. Thevalve 53 preferably has its own sensor 53′ connected by a sensor bus 10′to the circuit 4. It is alternatively or additionally possible toconnect the fresh air supply line 71, for example to the main supplyducts 7, 7′. A further sensor 71′ is positioned or connected to sensethe temperature, the pressure, and/or the air mass flow or volume in thefresh air supply line 71.

[0031] The FIGURE further shows sensors 11 and 12 which are preferablypart of the flight data management unit (FDMU) that is part of thecentral aircraft control. The sensor 11 measures the current altitudeand provides its output signal through a sensor databus 10′ to one inputof the updating computer 32. The sensor 12 comprises several sensorelements distributed inside and outside the aircraft for measuring thepressure and temperature at various points within the aircraft fuselageand outside thereof. A respective output of the sensor 12 is alsoconnected through a databus 10′ to the updating computer 32.

[0032] In operation, the data acquisition and conversion circuit 4processes all actual input data values received on the sensor conductorsor busses 10′ to provide actual data or values to one input of thecomparator 31. The performance characteristic computer 32, receives, inaddition to the data from the sensors 11 and 12 for performing updatingcalculations, the rated performance characteristic values or data fromthe memory 2. The computer calculates updated performance characteristicdata and provides at its output updated rated data or respective signalsto another input of the comparator 31. This updated rated signal isbased on the rated, standardized performance characteristic valuesstored in the memory 2 and on the current information regarding thepressure, temperature and altitude inside and outside of the aircraftfuselage as provided by the sensors 11 and 12.

[0033] The comparator 31 provides at its output 3 a closed loop controloutput signal that is supplied for example through the control bus 10A,10F to the turbo-engine 8 and through the control bus 10A, 10B to theair flow fan 52. The control signal at the output 3 is further suppliedthrough the control bus 10A, 10C to the flow control valve 51 in themain duct 7 and through the control bus 10A, 10D to the flow controlvalve 53 in the fresh air line 71. The control signal is furthersupplied through the control bus 10E to another air flow fan or blower52 in the main duct 7. A plurality of such fans or blowers may be placedthroughout the air distribution network.

[0034] By providing an updated or corrected rated performancecharacteristic input to the comparator 31, rather than a staticstandardized rated input, the closed loop control according to theinvention adapts the current air supply to the current flight conditionsof the aircraft, particularly during ascending and descending flight,whereby sensor signals measured inside the fuselage and even inside theair supply lines and ducts are taken into account as well as sensorsignals measured outside the aircraft.

[0035] The present control is a continuously progressing, iterativecontrol which avoids that too much air or too little air is supplied toany individual air outlet 9′ or air consumer at varying flightconditions and altitudes.

[0036] Although the invention has been described with reference tospecific example embodiments, it will be appreciated that it is intendedto cover all modifications and equivalents within the scope of theappended claims. It should also be understood that the presentdisclosure includes all possible combinations of any individual featuresrecited in any of the appended claims.

What is claimed is:
 1. A system for controlling, in closed loop fashion, an air mass flow inside an aircraft fuselage, said system comprising a controllable air mass flow distribution network including air flow pipes (7, 7′, 9, 71, 71′), at least one air outlet (9′) connected to one of said air flow pipes, at least one controllable air flow control element (8, 51, 52, 53) connected to said air flow pipes for moving air through said distribution network to said at least one air outlet (9′), a closed loop control unit (1) including a memory (2) for storing rated, first data representing at least one rated performance characteristic of said controllable air flow control element in said air mass flow distribution network, a plurality of sensors (5, 9″, 11, 12, 51′, 52′, 53′, 71′) positioned for sensing actual second data representing any of actual performance characteristics and actual pressure, temperature and altitude data, said closed loop control unit (1) further comprising a central processing unit including a computer (32) connected to said memory (2) and to said sensors (11, 12) for calculating updated performance characteristic rated data from said rated first and actual second data, a comparator (31) having a first input connected to an output of said computer (32) for receiving said updated rated performance characteristic data, said comparator (31) having a second input connected to said sensors (5, 9″, 52′, 53′, . . . ) for receiving said actual second data, said comparator (31) comprising an output (3) connected to said controllable air mass flow distribution network for providing a closed loop control signal for controlling said air mass flow.
 2. The system of claim 1 , further comprising a data acquisition and conversion circuit (4) as part of said closed loop control unit (1), said data acquisition and conversion circuit (4) comprising inputs connected to said sensors and an output connected to said comparator (31).
 3. The system of claim 1 , wherein said rated first data stored in said memory comprise data representing pressure loss first characteristics and static pressure second characteristics of said controllable air mass flow distribution network, and an optional third characteristic of at least one turbo-engine (8) for feeding fresh air into said air mass flow distribution network.
 4. The system of claim 3 , wherein at least one of said first, second and third characteristics is stored in said memory (2) in the form of one or more characteristic curves or fields of characteristic curves.
 5. The system of claim 1 , wherein at least one sensor of said plurality of sensors is arranged inside of at least one of said air flow pipes and wherein other sensors of said plurality of sensors are arranged inside and outside of said aircraft fuselage.
 6. The system of claim 5 , wherein said at least one sensor inside said at least one of said air flow pipes is one of a pressure sensor, a temperature sensor and an air flow volume sensor.
 7. The system of claim 5 , wherein said sensors comprise internal and external pressure sensors, internal and external temperature sensors, internal and external air flow sensors including flow volume sensors, and at least one altitude sensor.
 8. The system of claim 6 , wherein said external air flow volume sensors comprise at least one external air volume sensor positioned for measuring an air mass flow throughput of external air flowing downstream of said aircraft fuselage.
 9. The system of claim 2 , wherein said data acquisition and conversion circuit (4) also receives data from a flight data management unit of said aircraft fuselage including flight altitude data.
 10. The system of claim 1 , wherein said at least one controllable air flow control member comprises one of a controllable flow control valve and an r.p.m. controllable fan or blower.
 11. The system of claim 1 , wherein said computer (32) comprises a program memory having stored therein a computing algorithm (p_(c)=f(p, T) and/or p_(c)=f(H)) for correcting a rated performance characteristic of said air mass flow distribution network to provide said updated performance characteristic data to said first input of said comparator (31), wherein p_(c) is the cabin pressure, p is the current pressure, T is the temperature and H is the altitude.
 12. The system of claim 11 , wherein said computer (32) compares current performance characteristics of said distribution network measured at current actual pressures, actual temperatures and actual altitudes with performance characteristic data stored in said memory at respective pressure, temperature and altitude parameters to ascertain any deviations of current performance characteristic data from respective rated performance characteristic data, and for correcting said deviations to provide said updated performance characteristic data.
 13. The system of claim 11 , wherein said computer calculates deviations between said at least one rated performance characteristic stored in said memory (2) and a currently measured performance characteristic and then corrects any deviation to provide said updated performance characteristic data.
 14. The system of claim 1 , wherein said comparator output (3) and thus said closed loop control signal are connected through respective control signal busses (10A, 10B, 10C, 10D, 10E) to said at least one controllable air flow control member (51, 52).
 15. The system of claim 1 , wherein said controllable air mass flow distribution network comprises at least one turbo-engine (8) for supplying fresh air into said network, and wherein said turbo-engine (8) has a control input connected to said comparator output (3) for a closed loop control of said fresh air supply.
 16. A method for controlling, in closed loop fashion, an actual air volume or air mass flow in an air flow distribution network in an aircraft fuselage, said method comprising the following steps: (a) storing in a memory rated performance characteristic data of controllable air flow control elements (8, 51, 52, 53) of said air flow distribution network, (b) measuring actual pressure, temperature and altitude data and processing said actual data to provide actual updating signals, (c) updating said rated data with reference to said actual updating signals to provide updated performance characteristic data, (d) sensing at said controllable air flow control members actual performance characteristic data, (e) comparing said actual performance characteristic data with said updated performance characteristic data for generating a closed loop control signal, and (f) controlling at least one of said controllable air flow control elements in response to said closed loop control signal for keeping said actual air volume flow optimally close to a rated air volume flow.
 17. The method of claim 16 , wherein said step of measuring said actual pressure, temperature and altitude data is performed inside said aircraft fuselage.
 18. The method of claim 16 , wherein said step of measuring said actual pressure, temperature and altitude is performed outside said aircraft fuselage.
 19. The method of claim 16 , wherein said step of storing said rated performance characteristic values in said memory comprises storing performance characteristic curves or fields of curves in said memory.
 20. The method of claim 16 , wherein said step of updating said rated data comprises recalculating said rated performance characteristic data in response to any one of said actual updating signals to form said updated performance characteristic values. 